The Electronic Components of Clocks
It was never my intention to get into electronics, nothing could have been further from my mind. The idea of just winding a coil was challenge enough to give me heartburn. But after my experience with the Brian Law clock I thought the advantages of electrical powered clocks, even though I didn’t have the faintest idea how to make them, seemed to me to be overwhelming. Up to the introduction of electrical technology into the world of horology, clocks were mostly driven by a spring or heavy weight. When the spring or weight is wound up, the clock movement is under constant tension. It is this tension that drives the clock through a gradual tension release mechanism called an escapement.
Electric clocks that are driven by a magnetic coil are not under any tension at all. When the coil is energised it emits a magnetic field. This magnetic field can be used to attract an armature that is located at the bottom of a pendulum rod. As the pendulum rod is pulled forwards by the magnetic field, it can be used to push a wheel, known as a count wheel, which in turn drives the clock train. I think there are many advantages to this system but one of the less appreciated one is that it allows you to make pinions of softer metal. Most of the pinions in my clocks are made from brass rod. The pinions in more traditional clocks are made from hardened steel.
My early ideas came from the Scotts Clock, the first commercial electric clock manufactured by the Eveready Battery Company in the US, which used a mechanical switch to turn the coil on and off. I made a number of mechanical switches with varying degrees of success. But it was always obvious that the combination of the limitations of mechanical switches themselves combined with my very limited skills at building them meant that I was always on the hunt for a better solution. At one stage I even managed to get a Hipp Toggle system working but it was clunky, temperamental and completely unreliable.
On one occasion I was talking about the problem to a former radio tech I had met at a clock club I had joined. He said rather vaguely that what I needed was a slot switch. I had never heard of slot switches so I asked him for more information. It is not unkind to say that he was less than interested in helping and apart from providing a generic circuit with no details of any kind and which I did not understand anyway the conversation and contact ended.
That was when my practice of education via the internet began. I discovered that slot switches were used in photovoltaic switches and so I sent emails to any company or organisation who I could find on the net that had any connections with photovoltaics to see if I could find a switch. They all drew blanks. I was feeling a bit disappointed when I received an email from the administrator of the Australian National University in Canberra. He was very encouraging and said he had passed my email onto the engineering section of the university and that somebody would contact me. I confess to thinking I would not hold my breath.
Shortly after that I received an email from an engineer at the ANU named Bruce Condon. He asked me what I was trying to do and for the specifications of my coil and when I sent them to him he said he would build a switch. And he did! In due course this switch arrived in the mail (whenever I asked for a bill he ignored the email) with technical documentation but no instructions on how to use it. Eventually I figured out how to make use of it. Bruce went on to modify my switch to make it easier to use. When I talked to him about the voltage regulators I was building he sent me one he had made from the same kit I was using but his modification was much better than mine. I still use his modification in my voltage regulators.
My repeated request for a bill so I could reimburse him were ignored. So I sent him a small clock I had made with a quartz movement and he asked me why I did that. I have lost touch with him now but I have a debt of gratitude to Bruce Condon and I will never forget the assistance he gave me and for which he refused to allow me to pay. In this grasping world in which we live his act of kindness to a complete stranger is simply remarkable.
|My electronic clock journey begins. This was my first coil and pendulum experiment. As you can see Jess (the dog) looks bewildered by all the excitement. I tried to explain it to her but she just wants her dinner.|
|These are the electronic components for the slot switch controlled pendulum. It consists of a coil (about 10 ohms resistance) then a voltage regulator (Jaycar kit – modified) and the slot switch designed by Bruce Condon.|
|Schematic of the slot switch.|
After making a number of pendulum clocks I was looking for a better alternative. Basically what I wanted to do was to make smaller clocks and this was difficult as long as I was limited to the use of a pendulum. I am a member of a site on the net called ML Horology which is used by clock makers and would-be clock makers. One day one of the members of this site named Bruce Breimon who lives in California floated the idea of a different sort of switch/motor that used the same 32k crystal that is used in Quartz clocks. While I had little understanding of what he was talking about I was very interested. Bruce went on to develop the switch and also write the software to drive it and I reproduce it here with his permission because, like me, he is interested in helping anybody who has an interest in making clocks.
Bruce’s original idea was to make a clock that was similar to the Lazy Clock that has already been published on the internet. This is a highly ingenious clock that uses a solenoid to move the hands forward once a minute. I am told that some Russian horologists used a similar idea earlier in the last century. I don’t think there is much new in horology. What I wanted to do was to move hands more quickly than that and fortunately the software that Bruce wrote provided variables that could be changed to allow me to do this. Both Bruce and I have made a few modifications to his original switch but the basics remain the same. I remain deeply grateful to Bruce for his innovative thinking and his willingness to share it with this Australian bloke he has never met. Such is the nature of those engaged in horological pursuits. Sharing what you do and how you do it is the raison d’etre in the clock making community. Without this free exchange of ideas and expertise I would not be doing what I am now doing.
This is one of Bruce’s original switches. Behind the LED is an 8 legged integrated circuit. It is a 12f683 and I will talk a little more about it in the section on software.
This provides a second perspective of the switch.